Paddle wheel pick-ups or similar devices used for the extraction of minerals and for re-loading of bulk materials fail, if the specific cutting stress exceeds a limit. Beyond such limit there is considerable wear on blades and teeth. Furthermore, the high cutting power, which can change with the frequency of the charge figure, can place too much stress on the carriage. In order to extract minerals of high stability in a continuous process, it is recommended to separate the cutting process from the pick-up process, and to transmit the cutting forces in the most direct way to a carriage of sufficient load-carrying capacity.
German Pat. No. 209 273 discloses a breakdown apparatus in the general sense of the present patent application, which is for use in strip mining, particularly for lignite mining. Such known apparatus, however, cannot be operated during the cutting process as the pick-up is arranged directly below the cantilever beam on which the cutting device travels. When operating the device, the material would fall behind the pick-up making it impossible to take it up. For this reason, the known apparatus mines the front in strips over its entire height, before the apparatus may be moved by one cutting width on the carriage. This procedure is very complicated and time-consuming, and precludes a continuous operation. Furthermore, the known apparatus has the disadvantage that the cutting device cannot travel into the area where the pick-up is located, so that the latter must be moved away for cutting. Materials which resist cutting entail the disadvantages already mentioned. Others of extreme rigidity make such procedure completely impossible.